1. Field of the Invention
The present invention relates to an image forming apparatus provided with a detachable toner supply device that supplies a toner to an image forming unit.
2. Related Art
An image forming apparatus such as a copy machine, a printer, a facsimile machine, and a multi-functional printer having functions thereof are generally provided with an image forming unit that forms a toner image to be transferred to printing paper. To the image forming unit, a toner is supplied from a toner supply device (toner cartridge).
The toner supply device is configured for each model of the image forming apparatus. A compliant toner supply device for the model of the image forming apparatus is loaded into an installation space in an apparatus main body and supplies a toner to the image forming unit. Therefore, loading of a noncompliant toner supply device to the installation space in the apparatus main body and improper loading of a compliant toner supply device to the installation space (the toner supply device not fully inserted to an loading position) must be avoided.
As a technology for avoiding loading of a noncompliant toner supply device, a technology of forming a joint portion to be inserted into a developer container on a toner supply device of one model and forming a joint portion of a different shape on a toner supply device of another model has been known. In this technology, when a noncompliant toner supply device is loaded into an image forming apparatus, the joint portion thereof cannot be inserted into the developer container. Improper loading of the toner supply device can thus be avoided.
However, in this technology, when a toner supply device is loaded into an image forming apparatus, properness of the toner supply device is determined by physical interference upon insertion of the joint portion into the developer container. It is therefore difficult for an engineer to recognize a noncompliant toner supply device being loaded into the installation space. In addition, if a cover door body is closed in a state in which the noncompliant toner supply device is loaded into the installation space, an unexpected force is applied to the toner supply device and the toner supply device may break. And then, once the cover door body is closed, the engineer cannot recognize that the noncompliant toner supply device is being loaded into the installation space.